The present invention relates to a safety belt retractor and, more particularly, to an improved block-out mechanism that more reliably prevents during normal conditions the lockup of the reel on which the seat belt web is wound, while still allowing lockup of the reel in emergency situations.
Inertia-activated safety belt systems that prevent extraction of the safety belt from the reel based upon the acceleration forces exerted on its associated vehicle are conventional and well known. Such retractors generally include a safety belt wound on a reel that has ratchet wheels disposed on the opposite ends thereof. An inertia weight acts either directly or indirectly upon a lock bar to pivot the lock bar into locking engagement with the ratchet wheel teeth to prevent rotation of the reel so as to prevent further protraction of the safety belt therefrom.
Federal regulations have resulted in the increasing use of "automatic" or "passive" safety belt systems, i.e., safety belt systems that automatically position themselves about a vehicle occupant without any conscious effort of the occupant to utilize the system. Such systems often include door-mounted, safety belt retractors in which the safety belt is anchored inward of the occupant's seat and automatically crosses the occupant's body upon his or her entrance into the automobile and closing of the vehicle door.
During the opening of the car door, the inertia-sensitive, reel-locking device associated with the retractor on the door is likely to be subjected to acceleration forces sufficient to actuate the device and lock the retractor reel. This undesired locking of the reel, which would prevent the opening of the vehicle door, is, at the least, an annoyance to the vehicle user.
Consequently, it has been proposed that door-mounted safety belt retractors include a mechanism that operates, upon opening of the vehicle door, to block-out or prevent the lock bar from engaging the teeth of the ratchet wheels so that the safety belt may freely unwind from the reel. While the function of such lock bar block-out devices is to prevent the locking of the safety belt under acceleration forces typically encountered in the opening of the vehicle door, it may still be desirable to have the reel able to lock-up at very high force levels, e.g., three G's or greater when the door is open. However, because of these somewhat contradictory goals to block out the lock bar when the door is opened in the course of entering and exiting the vehicle, yet allowing the lock bar to engage the ratchet teeth of the belt reel and lock the reel against unwinding when the door is opened and at higher force levels, difficulties have been encountered in the design of an effective block-out device.
Accordingly, it is the principle object of the present invention to provide an improved lock bar block-out device for use in door-mounted safety belt retractors.
More particularly, it is an object to provide a lock bar block-out device that more reliably prevents the lock bar from engaging the ratchet teeth of the belt spool when the car door to which the retractor is mounted is opened for normal exiting and entering, but permits the lock bar to lock the reel against rotation when the car door is ajar and higher levels of acceleration are applied to the vehicle.
These objects, as well as others that will become apparent upon reference to the following detailed description and accompanying drawings, are provided by a door-mounted safety belt retractor having an elongated frame that rotatably supports a reel carrying a rolled safety belt and having a pair of ratchet wheels on the opposite ends thereof. A locking bar is pivotally mounted with respect to the frame for travel into engagement with the ratchet wheels to prevent protraction of the safety belt from the reel. An inertia-sensitive device is mounted on the frame and is movable with respect thereto to actuate the locking bar for engagement with the ratchet wheels. A block-out device for preventing the locking bar from engaging the ratchet wheels when the vehicle door is opened during normal entering and exiting of the vehicle includes a solenoid with a plunger movable in response to the opening of the car door. A rock lever is pivotally mounted with respect to the frame and operatively connected to the plunger. A block-out means is pivotally mounted and actuated by the rock lever between a non-blocking and a blocking position. The preferred block out means comprises a pivotally mounted member having a first end operatively connected to the lever and a second free end movable into a position to prevent engagement of the locking bar with the ratchet wheels.